In my review of the previous art in the field, the following patents were consulted:
Pat. No.InventorDate3,817,213ChalmarsJune 18, 19743,949,429HallApr. 13, 19763,964,437BrownJune 22, 19764,010,970CampbellMay 8, 19774,050,415Knochel et alSep. 27, 19774,117,555DennisOct. 3, 19784,185,861BernerMay 29, 19804,196,693UversawApr. 8, 19804,228,554TumminaroOct. 21, 19804,660,506NalvenApr. 28, 19876,014,946RymerJan. 18, 20006,039,370Dooley, Jr. et alMar. 31, 20006,457,435BridgesOct. 1, 20026,554,335Kelly, et alApr. 29, 20036,561,131SchwartzMay 13, 20036,568,348BedardMay 27, 2003
After a careful review of the listed patents it appears possible to group them under a few headings relative to their design and the difficulties and problems that might arise if they were in wide usage by the public.
The first grouping could be: Use of the Same Device By Both Animals and Humans. This is exemplified by the patents of Hall, 1976 and Rymer, 2000. These patents use a modified toilet seat that expands and contracts enough to manually arrange it as a seat for use by both humans and animals. Many humans would shy away from such use and it is very difficult to train an animal to void excreta while sitting or standing on a toilet stool seat.
The second grouping could be: Use of a Funnel Shaped Floor or Platform. This is presented in patents by Brown, 1976 and by Tumminaro, 1980. The sloping floor, while stable, creates a training problem for use by any animal and in the case of Brown required that a human push a button to initiate cleaning action.
The third grouping could be: Unstable Floor or Platform in order to initiate some mechanical action by downward movement of the floor. This is presented in patents by Knochel et al, 1977, Dennis, 1978, Unversaw, 1980, and Nalvern, weight down on a surface and it begins to move downward which would make training animals for this type of animal toilet very difficult.
The fourth grouping could be: The Use of Drain Holes for Removal of Excreta in a Flat Stable Board. This is exemplified by the patent of Bridges, 2002. Although it has the use of electronics to assist in the activation of cleaning of the flat stable board, there is no good mechanism for the cleaning of the underside of the board. It is removable to assist in this. The board also contains permanent open holes to allow the excreta to pass through. These holes are open while the animal is in the unit and constitute a hazard for harm to the legs of the animal.
The fifth group is probably not strictly an animal toilet so that it could be called: Catch Pouch on a Pole or a Pooper Bag. Both Dooley, 2000, and Kelly, 2003, present this concept very well in their patents. However, this system is not automatic and requires a great deal of human intervention.
The sixth group could be entitled: The Complex Litter Box. This concept is presented well in the patents of Schwartz, 2003, and Bedard, 2003. However, the use is limited to cats and involves special clumpable litter wherein the urine is removed as clumps of congealed litter along with fecal material by mechanical means such as rakes.
Although several patents have been issued for animal toilet inventions over many years, none have successfully solved the problem by presenting an acceptable method to the general public for rapid, simple economical disposal of dog and cat excreta. There has been no change in the handling of dog and cat excreta as compared to that of human excreta which has progressed from outdoor toilets to modern indoor toilets in bathrooms of first world people. A parallel development has been the invention of modern day washers and dryers for clothes and for dishes.